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Old 08-15-2017, 11:16 PM   #1 (permalink)
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2008 Honda Accord sedan aero improvements

Hi all,

Anyone done any worthwhile minor changes? Rear lip spoiler? Upper rear window spoiler? Or found that a full lower grill block is safe in weather from 70-95F(21-35C)?

Thanks!

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Old 08-16-2017, 11:15 AM   #2 (permalink)
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Define "worthwhile."

Most individual changes will be undetectable in the normal variability of tank-by-tank results. (Not the same as saying they don't work, just that the impact is small.)

I definitely wouldn't do a rear window spoiler on a sedan. That separates flow near the maximum cross section size. I'd consider a small decklid spoiler though. (Like the Civic Hybrid used.)

Off the top of my head, I'd consider (in order of effectiveness & ease):

- partial grille block (with ScanGauge to monitor coolant temps)
- passenger mirror delete
- smooth wheel discs
- passenger wiper delete / cowl block
- lower air dam
- rear wheel skirts
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Old 08-16-2017, 11:54 AM   #3 (permalink)
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Consider doing an upper grill block vs lower. Look at the corvette and other sports cars front layout where they intake cooling air almost always on the lower portion of the front. The bottom is messier for aero anyways, might as well keep the air path going over the car as smooth as possible.
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Old 08-16-2017, 12:35 PM   #4 (permalink)
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Having experience grille blocking 2 different accords, i've got some info for you.

Previously I had a 2005 4 cylinder 5mt, I could block MOST of the bottom grille, but not entirely or it would start to overheat. I don't remember which temperatures were too hot for it. Never tried an upper grille block on that car.

With my current 2006 V6 6mt I usually run a 60-70% lower grille block. Above 85 degrees and the fan kicks on a lot. When it drops below 50 degrees I can run a partial upper grille block, usually blocking half of the upper grille.

If you are willing, I strongly recommend pulling off the front bumper and making a panel to ensure the incoming airflow going to the lower grille does not bypass the radiator by going underneath it. I did this and a partially ducted grille block and was able to make the opening smaller while keeping the same cooling capacity, if not better.


Rear window spoiler: Absolutely not, you will only increase the drag.
Trunk lid spoiler: If you can get one for cheap/make one then you should consider it. This is something that will likely not pay itself back unless you DIY.


A full undertray will definitely be worthwhile as far as aero goes, but it is a lot of work. I've got a mostly full undertray on my car and it definitely improves coasting, as well as high speed stability.
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Old 08-16-2017, 12:52 PM   #5 (permalink)
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Daschicken - thanks!Was hoping you'd chime in with your first-hand experience.
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Old 08-16-2017, 11:56 PM   #6 (permalink)
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Thanks all! Anyone else care to chime in? I know this generation is incredibly smooth under the body.

Last edited by ScottDR; 08-17-2017 at 07:11 AM.. Reason: Mispell
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Old 08-18-2017, 12:11 PM   #7 (permalink)
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Quote:
Originally Posted by ScottDR View Post
Thanks all! Anyone else care to chime in? I know this generation is incredibly smooth under the body.
You sure about that? From what i've heard, the 8th gen accord drag coefficient is around .31 instead of the 7th gen's .30.

Here is the underside of a stock 7th gen
Click image for larger version

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Best trip in V6: 52.0
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Best tank in CBR: 61.3
Best tank in VFR: 62.5
Best tank in SV: 83.9

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Last edited by Daschicken; 08-18-2017 at 12:16 PM.. Reason: wrong drag coefficient
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Old 08-18-2017, 12:37 PM   #8 (permalink)
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Well, as sure as Honda is. They state 7G sedan was 0.34 and the 8G is 0.31here:

2008 Honda Accord - Body - Honda.com
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Old 08-18-2017, 12:58 PM   #9 (permalink)
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Quote:
Originally Posted by ScottDR View Post
Well, as sure as Honda is. They state 7G sedan was 0.34 and the 8G is 0.31here:

2008 Honda Accord - Body - Honda.com
I've looked into that before and came to the same conclusion that someone else has: Honda used the term "previous generation" very loosely. Those drag numbers are for the 6th gen accord.
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Best trip in V6: 52.0
Best tank in V6: 46.0
Best tank in CBR: 61.3
Best tank in VFR: 62.5
Best tank in SV: 83.9

Quote:
Originally Posted by MetroMPG View Post
You can lead a fashion-conscious horse to unusual-looking water...

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Old 08-24-2017, 07:14 PM   #10 (permalink)
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90 day: 42.15 mpg (US)

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Did you make a decision on any potential mods yet?

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-Kaze o tatakaimasen-

Best trip in V6: 52.0
Best tank in V6: 46.0
Best tank in CBR: 61.3
Best tank in VFR: 62.5
Best tank in SV: 83.9

Quote:
Originally Posted by MetroMPG View Post
You can lead a fashion-conscious horse to unusual-looking water...

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